Need to know the best technique to use for masking wall at ceiling.

I painted a bedroom a dried tomato color. The color is beautiful, but I’m not happy with results after pulling blue masking tape at the ceiling corner. It’s not even and looks terrible in some spots. I considered using caulking around entire room, around the ceiling. Have you ever had problems like this?

Oh yes! This usually happens with a rough knockdown texture. Very difficult to cut-in. I do one of two things, one of them you already mentioned.

A small amount of caulking at this corner makes a world of difference. After the caulking dries, you can cut-in free hand or use tape. Another option is to use tape, as you mentioned, with a small amount of caulking covering its edge at the corner. This accomplishes the same thing and saves a little time.

It's amazing what a little caulking can do to smooth out a rough texture. And, the best part is it isn't visible when everything is painted.